1. Field of the Invention
This invention concerns improvements relating to the operation of systems for raising net-type aircraft arresting gears.
At present, on take-off and landing strips or runways these arresting gears consist mainly of a net adapted to be raised in front of the aircraft in case of emergency, or alternatively of a cable extending across the strip in the case of aircrafts equipped with a special cross-head.
It is the essential object of the present invention to widen the field of possible uses for the net raising system proper.
2. Description of the Prior Art
The most popular systems employed for this purpose consist in raising a net disposed flat on the ground across the strip by means of posts driven in turn, either directly or through a cable, by a pneumatic or hydraulic cylinder controlled either from the control tower or from the barrier itself.
These devices generally consist of several independent elements, each submitted to high stresses. Their installation thus requires several supports accurately disposed the ones in relation with the other and adapted to absorb high stresses without any movement.
Moreover the lowering of the net is not positively ensured or, if yes, such lowering imposes a consumption of energy.
Furthermore, when the net is raised, holding the tension of the net suspension systematically involves a non-elastic deformation of this suspension and consequently a lowering of the net.
Finally the conceiving of these devices does not allow their complete housing into the ground for avoiding the presence of an obstacle at the strip end.